Actin Waves: Origin of Cell Polarization and Migration?

Actin filaments and associated proteins undergo wave-like movement in various cell types. Recent studies with cutting-edge analyses, including live-cell imaging, biophysical monitoring and manipulation, and mathematical modeling, have highlighted roles of 'actin waves' in cellular protrusion, polarization, and migration. The prevailing models to explain the wave-like dynamics of actin filaments involve an activator-inhibitor mechanism. In addition, axonal actin waves migrate by means of directional assembly and disassembly of membrane-anchored actin filaments, and thus represent a new type of machinery that translocates their component molecules to the cell edge. Here, we review recent advances in our understanding of the generation, mobility, and functions of actin waves, and discuss how actin waves may self-organize into the molecular machinery underlying cell morphogenesis.